/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package org.apache.naming;

import java.text.MessageFormat;
import java.util.Hashtable;
import java.util.Locale;
import java.util.MissingResourceException;
import java.util.ResourceBundle;

/**
 * An internationalization / localization helper class which reduces
 * the bother of handling ResourceBundles and takes care of the
 * common cases of message formating which otherwise require the
 * creation of Object arrays and such.
 * <p>
 * <p>The StringManager operates on a package basis. One StringManager
 * per package can be created and accessed via the getManager method
 * call.
 * <p>
 * <p>The StringManager will look for a ResourceBundle named by
 * the package name given plus the suffix of "LocalStrings". In
 * practice, this means that the localized information will be contained
 * in a LocalStrings.properties file located in the package
 * directory of the classpath.
 * <p>
 * <p>Please see the documentation for java.util.ResourceBundle for
 * more information.
 *
 * @author James Duncan Davidson [duncan@eng.sun.com]
 * @author James Todd [gonzo@eng.sun.com]
 * @author Mel Martinez [mmartinez@g1440.com]
 * @see java.util.ResourceBundle
 */
public class StringManager {

	private static final Hashtable<String, StringManager> managers =
			new Hashtable<String, StringManager>();
	/**
	 * The ResourceBundle for this StringManager.
	 */
	private final ResourceBundle bundle;
	private final Locale locale;

	/**
	 * Creates a new StringManager for a given package. This is a
	 * private method and all access to it is arbitrated by the
	 * static getManager method call so that only one StringManager
	 * per package will be created.
	 *
	 * @param packageName Name of package to create StringManager for.
	 */
	private StringManager(String packageName) {
		String bundleName = packageName + ".LocalStrings";
		ResourceBundle tempBundle = null;
		try {
			tempBundle = ResourceBundle.getBundle(bundleName, Locale.getDefault());
		} catch (MissingResourceException ex) {
			// Try from the current loader (that's the case for trusted apps)
			// Should only be required if using a TC5 style classloader structure
			// where common != shared != server
			ClassLoader cl = Thread.currentThread().getContextClassLoader();
			if (cl != null) {
				try {
					tempBundle = ResourceBundle.getBundle(
							bundleName, Locale.getDefault(), cl);
				} catch (MissingResourceException ex2) {
					// Ignore
				}
			}
		}
		// Get the actual locale, which may be different from the requested one
		if (tempBundle != null) {
			locale = tempBundle.getLocale();
		} else {
			locale = null;
		}
		bundle = tempBundle;
	}

	/**
	 * Get the StringManager for a particular package. If a manager for
	 * a package already exists, it will be reused, else a new
	 * StringManager will be created and returned.
	 *
	 * @param packageName The package name
	 * @return The instance associated with the given package
	 */
	public static final synchronized StringManager getManager(String packageName) {
		StringManager mgr = managers.get(packageName);
		if (mgr == null) {
			mgr = new StringManager(packageName);
			managers.put(packageName, mgr);
		}
		return mgr;
	}

	// --------------------------------------------------------------
	// STATIC SUPPORT METHODS
	// --------------------------------------------------------------

	public static final StringManager getManager(Class<?> clazz) {
		return getManager(clazz.getPackage().getName());
	}

	/**
	 * Get a string from the underlying resource bundle or return
	 * null if the String is not found.
	 *
	 * @param key to desired resource String
	 * @return resource String matching <i>key</i> from underlying
	 * bundle or null if not found.
	 * @throws IllegalArgumentException if <i>key</i> is null.
	 */
	public String getString(String key) {
		if (key == null) {
			String msg = "key may not have a null value";

			throw new IllegalArgumentException(msg);
		}

		String str = null;

		try {
			str = bundle.getString(key);
		} catch (MissingResourceException mre) {
			//bad: shouldn't mask an exception the following way:
			//   str = "[cannot find message associated with key '" + key + "' due to " + mre + "]";
			//     because it hides the fact that the String was missing
			//     from the calling code.
			//good: could just throw the exception (or wrap it in another)
			//      but that would probably cause much havoc on existing
			//      code.
			//better: consistent with container pattern to
			//      simply return null.  Calling code can then do
			//      a null check.
			str = null;
		}

		return str;
	}

	/**
	 * Get a string from the underlying resource bundle and format
	 * it with the given set of arguments.
	 *
	 * @param key  The key for the required message
	 * @param args The values to insert into the message
	 * @return The request string formatted with the provided arguments or the
	 * key if the key was not found.
	 */
	public String getString(final String key, final Object... args) {
		String value = getString(key);
		if (value == null) {
			value = key;
		}

		MessageFormat mf = new MessageFormat(value);
		mf.setLocale(locale);
		return mf.format(args, new StringBuffer(), null).toString();
	}
}
